Space & Science discoveries

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One of the most Earth-like planets in our galaxy Gliese 581d 'really does exist,' astronomers say



Astronomers have found new evidence of the existence of an Earth-like planet that lies a comparative stone’s throw away from our solar system.


Discovery of the planet known as GJ 581d was heralded in 2007 but new research last year cast doubt on the claims, saying data used to find it was probably just misinterpreted signals from stars.


Astronomers had used a spectrometer to spot the planet, which measures “wobbles” in the wavelength of light emitted by a star caused as a planet orbits it.

GJ 581d was said to be a super-Earth with a mass seven times that of our own planet orbiting a red dwarf star that could also support up to four other planets.




It was believed to be in the habitable “Goldilocks zone” in its solar system, where it is neither too hot nor too cold for liquid water to exist and support life on the surface.

Researchers revisiting the evidence claimed the body was actually just “stellar activity masquerading as planets” and its existence was widely dismissed without further questioning.

But now astronomers from Queen Mary University, in London, and the University of Hertfordshire have claimed the statistical techniques used to discount GJ 581d is “inadequate” for planets of its small size.

Dr Guillem Anglada-Escudé, lead author of the paper published in Science, said: “The existence (or not) of GJ 581d is significant because it was the first Earth-like planet discovered in the ‘Goldilocks’-zone around another star and it is a benchmark case for the Doppler technique.

“There are always discussions among scientists about the ways we interpret data but I’m confident that GJ 581d has been in orbit around (its star) Gliese 581 all along.”



An artist's impression of Kepler-186f which may also have conditions suitable to life

She said the method worked for identifying larger planets in the past because their effect on the star was so significant it outweighed errors in the findings.

However, she argued that the technique makes it almost impossible to find the smallest planet signals close to or within the noise caused by the stellar own variability.

If GJ 581d does exist, it could be of the most Earth-like planets yet discovered as ranked by the Earth Similarity Index but that does not mean its surface is the same.

Some studies have suggested Gliese 581d's denser air and dim red light from its host star would make for a murky environment that would be toxic to humans.

The Index incorporates a number of factors including surface temperature and planet density to rank extrasolar planets in a scale from 0 to 1. The most Earth-like planet yet confirmed is Gliese 581g, orbiting the same star, which ranks at 0.89.

For astronomers, the most exciting aspect is its relative proximity – 20 light years away in a galaxy that is 100,000 light years wide.

Robin Wordsworth, who researched Gliese 581d with the Institut Pierre Simon Laplace in Paris, said: "The Gliese system is particularly exciting to us as it's very close to Earth, relatively speaking. So with future generations of telescopes, we'll be able to search for life on Gliese 581d directly."

source Independent
 
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    Beginnings of life found in young star system



    Scientists have found the basic beginnings of life elsewhere in the universe, for the first time ever in a disc around a young star.

    Scientists used observations from a huge telescope in Chile to see that a disc — on its way to becoming a planet — surrounding a young star is filled with methyl cyanide. That is a complex, carbon-based molecule which is found in huge quantities around the star.

    Since comets keep a record of the early solar system, while planets were being formed. Comets and asteroids like those holding the molecules are thought to have put the water and other material on early Earth that helped make conditions for life.

    The discoveries show that such materials, likely to be necessary for life to form anywhere, are present elsewhere in the universe. They are also in similar concentrations to those found in our solar system.



    The disc that surrounds the star — which is known as MWC 480, is twice as big as the Sun and is 455 light-years away — is still becoming developed, and so isn’t ready to hold life of its own. But the discovery shows that the conditions that created life on Earth are not unique, and are likely to exist elsewhere in the universe too.

    Scientists have long known that the clouds that exist in space would be good at creating the complex molecules. But they didn’t know whether that meant that they did form — since the shock and radiation found there could easily destroy them as soon as they started — but the new discovery shows that they have been.

    The research was conducted using the Atacama Large Millimeter/submilliimeter Array (ALMA), which is in the Chilean Andes and is the biggest ground-based astronomical project in the world. It is run by the European Southern Observatory with partners from around the world, and looks out towards some of the coldest parts of the universe to try and find out about how the universe and our planets came into being.

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    'Dark matter' not as dark as first thought: Scientists find it interacts with forces other than just gravity

    Dark matter may not be so dark after all, after scientists witnessed the mysterious cosmic entity interacting with the universe around it an entirely new way.


    Despite accounting for an estimated 85 per cent of matter in the Universe, dark matter has never been seen directly by any scientific instruments. Its existence has only been inferred by its gravitational effects.



    But astronomers have now for the first time witnessed dark matter apparently “slowing down” after interaction with other dark matter - suggesting it is capable of engaging with a force other than gravity.


    “We used to think that dark matter sits around, minding its own business. But if it slowed down during this collision, this could be the first dynamical evidence that dark matter notices the world around it,” said Richard Massey of Durham University. who led the research.

    “Dark matter may not be completely ‘dark’ after all.”

    Dark matter can only be detected indirectly by the way it bends the light of distant galaxies in a process known as gravitational lensing.

    Exploiting this phenomenon, an international team of astronomers using the Hubble Space Telescope took images of a massive simultaneous collision in deep space between four distant galaxies.

    The researchers found that the dark matter associated with the colliding galaxies has become disconnected with this visible mass of colliding stars, suggesting that it has come under the influence of a force other than gravity, probably by interacting with itself.

    “The observations show that dark matter has ended up in a different place to the stars in the galaxy it was associated with. It has become offset in some way, and that’s pretty unusual,” Dr Massey said.

    “We’ve been trying to think of other things that would cause this offset and there’s nothing else we can think of that would have this effect other than dark matter interacting with itself. This is the first step in figuring out what dark matter is. To see it behaving in this way is the first positive thing we’ve seen dark matter do,” he added.

    An earlier study published last month examined the behaviour of dark matter during 72 “high speed” collisions of clusters containing thousands of galaxies. This suggested very little or no interaction between dark matter.

    However, the latest study published this week in the Monthly Notices of the Royal Astronomical Society examined the relatively slower speed collision of just four galaxies in a cluster known as Abell 3827, which took place over hundreds of millions of years.

    The different nature of this collision means that even a very low level of interaction can eventually create a detectable lag between the galaxy’s dark matter and its stars, which continued to collide, Dr Massey said.

    Professor Liliya Williams of the University of Minnesota, a senior member of the team, said: “Our observation suggests that dark matter might be able to interact with more forces than just gravity. The parallel Universe going on around us has just got more interesting. The dark sector could contain rich physics and potentially complex behaviour.”

    Calculations suggest that the clump of dark matter associated with cluster of four galaxies is offset in space by a distance of about 5,000 light years, equivalent to about 50,000 million million kilometres – a distance that would take Nasa Voyager spacecraft, the most distant man-made object, some 90 million years to travel.

    “It sounds a long way but in cosmic terms it’s actually quite small. We were lucky to see it and it was only possible because of the power of the Hubble space telescope and the fact that one of the galaxies was perfectly aligned so that we could see the gravitational lensing effect,” Dr Massey said.

    Explainer: What the historic picture above shows

    The four galaxies in this cluster are involved in a massive collision taking place over a period of hundreds of millions of years. As the topmost of the four galaxies in the image begins to collide, it has left its dark matter trailing behind.

    The dark matter in this image is invisible, but it can be detected by the way it bends the light of an even more distant galaxy, in a process known as gravitational lensing, which has left a distorted image seen here as an arc of blue light just to the right of the cluster.

    The discovery that dark matters trails behind galaxies in this way suggests it is not perfectly ‘dark’ after all.

    source independent

     
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    Nasa is confident about finding life on Europa in its next mission



    Nasa has given details on how it hopes to find life on Jupiter's moon Europa in a mission launching in the 2020s that will seek to determine if the satellite is habitable.

    It is thought that beneath Europa's icy surface there is an ocean sitting on a rocky bed punctured by hydrothermal vents that could circulate heat and nutrients.

    "After five billion years with conditions like that, it could be a very habitable place," said Jim Green, director of NASA's planetary science division, at a news conference. "We believe the environment is just perfect for the potential development of life."

    If life of any description is discovered, it will surely be the biggest news in our entire human history.

    "If we do find life or indications of life that will be an enormous step forward in our understanding of our place in the universe," Green added. "If there's life in the solar system and in Europa in particular, it must be everywhere in our galaxy and perhaps even in the universe."

    Hydrothermal vents on Earth are teaming with life, so there is certainly a chance that organisms of some kind persist on Europa's.

    The spacecraft Nasa is creating for the mission will use nine different instruments to determine whether the moon is habitable, though it will have no "life detectors" as such, with 'life' as we define it being somewhat difficult to confirm with certainty given what an unknown quantity any extra-terrestrial creatures would be.

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    Monster Hurricane on Saturn

    NASA's Cassini spacecraft has provided scientists the first close-up, visible-light views of a behemoth hurricane swirling around Saturn's north pole. In high-resolution pictures and video, scientists see the hurricane's eye is about 1,250 miles (2,000 kilometers) wide, 20 times larger than the average hurricane eye on Earth. Thin, bright clouds at the outer edge of the hurricane are traveling 330 mph(150 meters per second). The hurricane swirls inside a large, mysterious, six-sided weather pattern known as the hexagon.

    “We did a double take when we saw this vortex because it looks so much like a hurricane on Earth”, said Andrew Ingersoll, a Cassini imaging team member at the California Institute of Technology in Pasadena. “But there it is at Saturn, on a much larger scale, and it is somehow getting by on the small amounts of water vapor in Saturn's hydrogen atmosphere”.


    A major difference between the hurricanes is that the one on Saturn is much bigger than its counterparts on Earth and spins surprisingly fast. At Saturn, the wind in the eye wall blows more than four times faster than hurricane-force winds on Earth. Unlike terrestrial hurricanes, which tend to move, the Saturnian hurricane is locked onto the planet's north pole. On Earth, hurricanes tend to drift northward because of the forces acting on the fast swirls of wind as the planet rotates. The one on Saturn does not drift and is already as far north as it can be.

    “The polar hurricane has nowhere else to go, and that's likely why it's stuck at the pole”, said Kunio Sayanagi, a Cassini imaging team associate at Hampton University in Hampton, Va.

    Scientists believe the massive storm has been churning for years. When Cassini arrived in the Saturn system in 2004, Saturn's north pole was dark because the planet was in the middle of its north polar winter. During that time, the Cassini spacecraft's composite infrared spectrometer and visual and infrared mapping spectrometer detected a great vortex, but a visible-light view had to wait for the passing of the equinox in August 2009. Only then did sunlight begin flooding Saturn's northern hemisphere. The view required a change in the angle of Cassini's orbits around Saturn so the spacecraft could see the poles.



    The north pole of Saturn, in the fresh light of spring, is revealed in this color image from NASA's Cassini spacecraft.



    The spinning vortex of Saturn's north polar storm resembles a deep red rose of giant proportions surrounded by green foliage in this false-color image from NASA's Cassini spacecraft.



    This spectacular, vertigo inducing, false-color image from NASA's Cassini mission highlights the storms at Saturn's north pole.
     
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    Nobody panic, but a 'monster' dormant black hole has just woken up



    In news that's kind of awesome but also kind of scary, the European Space Agency (ESA) has said that a "monster" black hole has become active again after being dormant for 26 years.


    Scientists have observed the black hole in V404 Cygni, a binary system 8,000 light-years away, has started eating its neighbouring star creating a beautiful high-energy interstellar light show.


    X-rays and gamma rays picked up the black hole feasting as it hoovers up material and light from the star. As it draws closer to the black hole, the light emissions from the star heat up and gather in a disc that shines brightly on wavelengths across the electromagnetic spectrum before spiralling into the matter-eating monster.



    The Japanese and American space agencies first noticed the black hole's renewed activity last week. Astronomers around the world are thrilled with the chance to witness the rare out-bursting black hole.

    The behaviour of this source is extraordinary at the moment, with repeated bright flashes of light on time scales shorter than an hour, something rarely seen in other black hole systems. In these moments, it becomes the brightest object in the X-ray sky – up to fifty times brighter than the Crab Nebula, normally one of the brightest sources in the high-energy sky.

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    Amazing engineering feat...

    NASA probe finally on Pluto’s doorstep

    Posted on July 12, 2015 by William Harwood

    STORY WRITTEN FOR CBS NEWS & USED WITH PERMISSION


    Artist’s concept of the New Horizons spacecraft. Credit: NASA/JHUAPL/SWRI

    Three billion miles and nine-and-a-half years from Earth, NASA’s New Horizons probe is racing toward a historic July 14 flyby of Pluto, providing the first close-up views of the most famous denizen of the Kuiper Belt, a vast hinterland where uncounted remnants of the solar system’s birth orbit in frozen solitude.

    Famously demoted from planethood, Pluto, its large moon Charon and its four other known satellites have been elevated to rock star status in recent weeks as New Horizons has hurtled ever closer, beaming back increasingly sharp pictures of a remote world on the outer limits of humanity’s reach.

    Recent photos have revealed an apparent polar cap, huge dark spots stretched along the reddish world’s equator and even surface features on Charon, a Texas-size moon that orbits Pluto in gravitational lockstep every 6.4 days.

    But the best is yet to come.

    For principal investigator Alan Stern and a dedicated team of scientists and engineers who first proposed a Pluto mission back in 1989, the coming flyby represents the “capstone” of the initial reconnaissance of the solar system, the first visit to a new world since Voyager 2’s flybys of Uranus and Neptune in 1986 and 1989.

    “It’s taken a long time to get this thing funded and built and flown across the solar system, but in the next few (days), we’re going to rock people’s socks, and I think if we do it right, we’ll have the eyes of the world on us,” Stern, a senior scientist at the Southwest Research Institute, told CBS News.

    The $720 million mission is reminiscent of “the 1960s or 70s, when everything was brand new exploration, but done with 21st century technology. And it’s been a generation since Voyager. Half the people in the United States are too young to remember Voyager.”

    “They’ve never seen what you saw as a boy — Mars go from a point of light to a planet. Jupiter and its moons do the same thing, then Saturn, then Uranus, then Neptune. They’ve never seen anything like this in any country around the world.

    “So we know we’re going to really fire people up, they’re going to see this place, Pluto, become a real, complicated, frontier world. I hope we can enthuse kids to go into science and math and engineering, just to say that is a cool thing we did!”

    Mike Brown, a planetary astronomer who led the discovery of several Pluto-like worlds in the Kuiper Belt and a leading proponent of the “Pluto is not a planet” school of thought, said the New Horizons mission represents “our only chance to see what any of the objects out there are like, and this will inform everything we think about all the objects out there.”

    “I’m actually a lot more excited now than I even was when New Horizons was being conceived,” Brown, who is not part of the New Horizons project, said in an interview. “Way back then, Pluto was just this oddball at the edge of the solar system. And now, we know it’s just one of many things like it that we’re going to learn about, this whole class of objects, which is an exciting thing to get to do.”


    New Horizons’ Long Range Reconnaissance Imager captured this view of Pluto early Saturday, July 11, at a distance of 2.5 million miles (4 million kilometers). It shows mysterious dark spots along Pluto’s equatorial belt and linear features suggestive of polygonal shapes. Credit: NASA/JHUAPL/SWRI

    Built by the Johns Hopkins University Applied Physics Laboratory, New Horizons will make its closest approach to Pluto at 7:49:57 a.m. EDT (GMT-4) on July 14, passing within about 7,750 miles of the dwarf planet’s surface at more than 31,000 miles per hour. The spacecraft’s cameras will be able to resolve surface features as small as a softball field.

    Fourteen minutes later, the spacecraft will make its closest approach to Charon, a more distant 17,900 miles from the moon’s surface.

    In a remarkable feat of celestial navigation, New Horizons will fly into Pluto’s shadow 47 minutes and 28 seconds after the Charon flyby, orienting itself so its high-gain antenna and instruments can record how Pluto’s tenuous nitrogen-methane atmosphere affects sunlight and radio signals from Earth as they pass through.

    “After we pass by Pluto, we then fly into Pluto’s shadow at the same time while we’re looking at radio beams coming up from the Deep Space Network … measuring the structure of Pluto’s atmosphere, the temperature and the mass of Pluto’s atmosphere,” said Hal Weaver, the New Horizons project scientist.

    “At the same time, the ultraviolet spectrograph, the Alice instrument, will be observing the sun and by looking at the absorption of sunlight as we pass behind Pluto’s atmosphere, we get the signature of the composition of Pluto’s upper atmosphere.”

    Just one minute and two seconds after entering the shadow cone, New Horizons will move back into sunlight and one hour and 25 minutes after that, the spacecraft will pass through the shadow of Charon, again searching for evidence of an atmosphere.

    Throughout the approach and departure, New Horizons’ sensitive cameras and other instruments will study the other known moons — Hydra, Nix, Kerberos and tiny Styx — and will attempt to map Pluto’s dark side, illuminated by sunlight reflected from Charon.

    They also will search for any signs of cryogenic geysers like those seen on Neptune’s moon Triton, which many astronomers believe is a captured Kuiper Belt body. Pluto may harbor an ocean of liquid water below its icy crust.

    “This is a scientific wonderland,” Stern told reporters earlier this year. “It is a binary (planet). Pluto and it’s large, Texas-size moon Charon, half its size, are like nothing we have ever visited in the history of planetary exploration. And surrounding that binary is a circumbinary system of at least four more, much smaller moons.”

    Despite its vast distance from the sun and a surface temperature around 387 degrees below zero Fahrenheit, Pluto is “a very complex body,” Stern said.

    “It has an atmosphere, it has seasons, the surface markings have been moving over time, probably indicating shifting snows and some sort of process of exchange between the atmosphere and the surface. We’ve seen the atmospheric pressure double or perhaps triple over time, we know that it’s rocky on the inside and icy on the outside.”

    The presence of nitrogen, carbon monoxide and methane “make for probably the most complex system of interactions we have ever seen in the history of exploration between surface and atmosphere,” Stern said.

    And then there’s Charon, which Stern called “the rising star of this mission.”

    “It has no volatiles on its surface, only water ice,” he said. “It has a much less rocky interior. To our knowledge, it has no atmosphere. But there are tantalizing signs of surface activity. … We’re going to see which of those things are actually the case and what this pair has in store for us.”

    At a distance of more than three billion miles and moving ever more distant, using 12-watt radio transmitters and a relatively small antenna, it will take New Horizons some 16 months to play back all of its recorded data.

    “Although the spacecraft will be long gone from the Pluto system after July, we will be making discoveries as a science team and communicating them to the world for 16 months as new data sets come to the ground, as if we were still there in orbit,” Stern said. “This is really a different mode of flyby than has ever been done because we have the capability to collect a large amount of data.”

    And when its done with Pluto, New Horizons will continue its lonely mission, flying past at least one more Kuiper Belt object in 2019 before departing the solar system and heading out into interstellar space.

    SEARCHING FOR “PLANET X”

    At the turn of the 20th century, Neptune was the eighth and outermost known planet. But astronomer Percival Lowell, founder of the Lowell Observatory in Flagstaff, Arizona, believed a ninth planet likely lurked in the darkness beyond and he believed it could be found by looking for subtle gravitational perturbations in the orbits of Uranus and Neptune.

    Three unsuccessful searches for “Planet X” were carried out before Lowell died in 1916. But the Lowell Observatory continued the search, hiring amateur Clyde Tombaugh to carry out painstaking observations.

    Taking pictures of the same area of the night sky several days apart, Tombaugh used an instrument called a blink comparator to examine two plates mounted side by side, switching back and forth between the two views to look for anything that appeared to move against the fixed background stars.

    Astronomers believed there were two likely areas of the sky to examine for a ninth planet but as it turned out their calculations were flawed. Even so, by a combination of luck and diligence, Tombaugh finally succeeded on Feb. 18, 1930. He had found Lowell’s ninth planet.

    “In the little cluster of orbs which scampers across the sidereal abyss under the name of the solar system there are, be it known, nine instead of a mere eight, worlds,” the Associated Press reported. “Way out beyond Neptune, tagging bashfully behind its brothers, the new planet’s exact whereabouts, size and age are still unknown and it has not even a name.”

    But Pluto, as it came to be known, turned out to be much smaller than the observatory’s founder expected, and it was so far away little could be discerned about its nature beyond the basics of its orbit.


    Clyde Tombaugh, discoverer of Pluto. Credit: Lowell Observatory Archives

    Over the years, astronomers filled in many of the blanks, finding that Pluto circles the sun in a 247.7-year elliptical orbit tilted 17 degrees to the plane of the other planets, an orbit carrying it as close as 2.8 billion miles from the sun and as far as 4.6 billion miles. Between 1979 and 1999, Pluto was closer to the sun than Neptune.

    The ice dwarf is tipped over on its side and has a diameter of about 1,470 miles. Gravity is about 6 percent of Earth’s and surface temperatures are as low as 387 degrees below zero Fahrenheit. Astronomers have detected spectroscopic signs of nitrogen, carbon monoxide, methane and ice on the surface.

    The distant world has an extremely thin atmosphere composed of nitrogen with small amounts of methane, carbon monoxide and other hydrocarbons.

    For nearly 50 years, Pluto was little more than a dim point of light on photographic plates and, eventually, CCD detectors. But in 1978, U.S. Naval Observatory astronomer James Christy discovered a large moon orbiting Pluto. He named it Charon, after his wife Charlene. The name also refers to the ferryman of the dead in Greek mythology.

    Pluto and Charon whirl about each other every 6.4 days at a distance of about 12,200 miles, turning in gravitational lockstep and always keeping the same face toward each other.

    At 745 miles across, Charon is about nearly half the size of Pluto and the two orbit a common center of gravity, or barycenter, well above Pluto’s surface. For that reason, Pluto is viewed as a “binary planet,” the only such worlds yet discovered. Four other, much smaller moons, were discovered by the Hubble Space Telescope in 2005, 2011 and 2012.

    The origin of the Pluto-Charon system is not known with certainty, but scientists believe a large body crashed into Pluto shortly after the solar system’s formation 4.6 billion years ago. Material from the impactor and Pluto was blown into space and later coalesced to form Charon. Pluto’s other four moons are thought to be made up of surviving remnants of the great crash.

    In more general terms, Pluto is now thought to be the largest, or one of the largest, bodies making up the Kuiper Belt, a vast realm stretching two billion miles beyond the orbit of Neptune where debris left over from the formation of the solar system slowly orbits.

    The existence of the Kuiper Belt was confirmed in 1992 when the first Kuiper Belt Object, or KBO, was discovered, a body 10,000 times fainter than Pluto. Since then, more than 1,000 icy KBOs have been discovered, ranging from 30 to more than 1,200 miles across. One of them, Eris, appears to be slightly larger than Pluto.

    All told, the Kuiper Belt may include more than 100,000 bodies with diameters greater than 60 miles.


    The Hubble Space Telescope’s Faint Object Camera took this image of Pluto and Charon in 1994. Credit: Dr. R. Albrecht, ESA/ESO Space Telescope European Coordinating Facility; NASA

    Planetary scientists now view the solar system as made up of three distinct zones. Closest to the sun are the rocky terrestrial planets: Mercury, Venus, Earth and Mars. Then come the gas giants, Jupiter, Saturn, Uranus and Neptune. And now comes the Kuiper Belt and its most famous member.

    Pluto was known as an “ice dwarf” even before the International Astronomical Union officially changed its designation from “planet” to “dwarf planet” in 2006. And despite its famous — or infamous — demotion, Pluto has lost none of its luster.

    “Pluto is a brand now, it’s essentially a brand,” Stern said. “Everybody knows what it is, and there’s intense interest in this. It’s small and diminutive, that may be part of it. It’s on the far frontier, that’s part of it. It’s the one that everybody and their kid’s textbooks, when you got to Pluto, it was all question marks, it didn’t have a picture, didn’t know the size, didn’t know the atmosphere, didn’t know anything.”

    All of that’s about to change.

    NEW HORIZONS’ COMPLEX CHOREOGRAPHY

    New Horizons’ flyby of Pluto is an extraordinarily complex undertaking, one that requires split-second timing as the spacecraft autonomously carries out hundreds of observations while streaking through the Pluto-Charon system at more than 31,000 mph.

    At some three billion miles from Earth, the spacecraft is far beyond any sort of real-time guidance.

    Because New Horizons’ instruments cannot be independently aimed, the entire spacecraft must constantly re-orient itself to make the desired science observations as it moves through the Pluto system, turning this way and that, following a complex set of commands radioed up from Earth before the encounter.

    And while the flyby science is being carried out, New Horizons’ high-gain antenna will not be pointed at Earth. The spacecraft must operate autonomously, storing its collected images and other data on solid-state recorders for later transmission to Earth.

    On July 14, no data is expected on Earth beyond a signal around 9 p.m. that evening telling flight controllers the spacecraft survived the flyby. The first close-approach images are expected the next day. But the full set of high-resolution images and data is expected to take 16 months to transmit to Earth.

    “The craft will be operating itself, we won’t be joy-sticking it from mission control, it will have what’s called a command sequence, a program of instructions,” Stern said. “They’ve been simulated on the ground, and we’ve even put that command sequence on the spacecraft in flight and had it run through the Pluto encounter out in the middle of nowhere. So it’s pretty well rehearsed.”

    All in all, he said, “there are something more than a thousand scientific observations in that sequence among the seven instruments. Pluto, five moons, there are a lot of targets, a lot of data sets we collect.”


    Alan Stern (center) and members of the New Horizons science team react to seeing new images of Pluto for the first time. Credit: Michael Soluri

    And timing is critical. For the command sequence to make the desired observations, New Horizons must fly through an imaginary close-approach target in space measuring 60 by 90 miles within a window just 100 seconds long. And hitting that box on time means understanding exactly where Pluto and the spacecraft are with respect to each other.

    Over the past several weeks, New Horizons’ Long-Range Reconnaissance Imager, or LORRI, camera was used to precisely measure Pluto’s position with respect to background stars, helping scientists pin down the dwarf planet’s exact location and orbital track. The camera also was used to look for uncharted moons or even rings that might pose a threat to the spacecraft.

    No such threats were identified and on June 29, a final 23-second trajectory correction maneuver was carried out to ensure the proper flyby geometry and timing.

    “So we’re flying three billion miles, we have to hit a target 60 by 90 miles and we have to hit it within 100 seconds after nine-and-a-half years,” said Glen Fountain, the New Horizons project manager. “That’s the kind of precision we have to navigate to.”

    “Not only do we have to hit this one point in the system as we fly by at closest approach, but we have to also fly through in such a way, we have to thread the needle so that we pass through the shadow of Pluto and then the shadow of Charon. Just to make it a little more difficult! … And with that, we collect the data and we turn around and send it home.”

    But there are no guarantees.

    On July 4, an unexpected processing overload on the spacecraft’s primary flight computer prompted its autopilot to switch over to a backup computer, putting the probe in “safe mode” and interrupting communications with Earth. The problem was quickly diagnosed and normal operations resumed two days later.

    But the loss-of-contact, however brief, reminded everyone of the risks involved with operating a spacecraft on the edge of the solar system.

    “We are so far away, it’s a nine-hour round-trip light time, so the spacecraft has to operate on its own,” Fountain said. “We can’t rely upon the kind of ground intervention, as good as it is, to be able to do anything.”

    Instead, starting seven days out, New Horizons began operating with “encounter mode” software logic for the make-or-break flyby.

    “Instead of going safe as it did (July 4) the spacecraft will automatically return to the preprogrammed timeline to continue gathering data,” Fountain said. “We will have that as our belt and suspenders as we go through the encounter itself.”

    But New Horizons is a one-shot deal. It cannot slow down or come back for a second chance. Even before the recent glitch, Weaver said “the stress level is pretty high. The damn thing better work, too!”

    “We’ve done as much as we can. But you’re only as strong as your weakest link. But things have worked so beautifully for the past nine years, it seems like it will continue to work and we’ll be successful. But it remains to be seen.”


    New Horizons launched from Cape Canaveral on Jan. 19, 2006, aboard an Atlas 5 rocket. Credit: NASA

    PACKING LIGHT FOR A VERY LONG TRIP

    New Horizons began its long journey on Jan. 19, 2006, blasting off atop the most powerful version of a United Launch Alliance Atlas 5 rocket.

    The lightest payload ever launched by an Atlas 5, a rocket normally used to boost heavy spy satellites and large NASA payloads into orbit, New Horizons was propelled to a record departure velocity of 36,000 mph — 10 miles per second — fast enough to cross the moon’s orbit in just nine hours. It took the Apollo astronauts more than three days.

    New Horizons crossed the orbit of Mars less than three months after launch, raced through the asteroid belt and got to Jupiter in a record 13 months for a velocity-boosting gravity-assist flyby that shaved 3.7 years off the trip. The Jupiter flyby also gave the science team an opportunity to thoroughly test the probe’s instruments.

    Once past Jupiter, New Horizons spent two thirds of the remaining voyage to Pluto — 1,873 days — in electronic hibernation, periodically waking up and phoning home to downlink health data and to receive software updates.

    The engineering team took advantage of the down time to upload and carry out a full-scale dress rehearsal of the Pluto flyby, re-orienting the spacecraft and operating its instruments exactly as required during the real thing.

    And then it went back to sleep, all the while covering more than three-quarters of a million miles per day. All told, the trip took nine-and-a-half years.

    To put that that immense distance in perspective, imagine the sun the size of a quarter on the goal line of a football stadium. At that scale, Earth, just nine-thousandths of an inch across, would be three yards away. Pluto would be an invisible speck 18 yards beyond the far goal line.

    To even consider such a voyage, mission planners knew they had to pack as much science capability as possible into a very lightweight, low-power package. Every pound counted.

    “This is a small, compact, highly advanced spacecraft, a real 21st century exploration spacecraft with tremendous capability,” Stern said. “If you weighed all seven instruments aboard New Horizons, the combined weight of these seven very advanced instruments is less than just the camera on the Cassini Saturn orbiter.

    “And if they were all running at once, they would draw only 28 watts, about half a standard 60-watt light bulb. Isn’t that amazing? I never get over that. It’s a real tribute to the engineers.”

    New Horizons is a lightweight compared to the school bus-sized Cassini spacecraft, measuring just 27-by-83-by-108 inches and weighing 1,054 pounds at launch, of which 170 pounds was hydrazine maneuvering fuel. It’s roughly triangular and about the size of a baby grand piano.

    At Pluto’s enormous distance from the sun, solar panels are not a viable option. Instead, New Horizons relies on a single radioisotope thermoelectric generator, or RTG, for electrical power, using thermocouples and the heat produced by the decay of plutonium 238 dioxide to generate electricity.

    Seven state-of-the-art science instruments are on board, including a radio system that will be used to both communicate with Earth and to collect valuable data about Pluto’s tenuous atmosphere. The instruments typically operate on less power than a night light – two to 10 watts each. Recalling “The Honeymooners” TV series and Ralph Kramden’s frequent outbursts of “to the moon, Alice,” two of the instruments are named Ralph and Alice.

    Operating more than 30 times farther from the sun than Earth, New Horizons is built like a thermos bottle and insulated to retain the heat generated by its electrical systems. Internal temperatures between 50 and 85 degrees Fahrenheit are expected throughout the mission, but small heaters are available just in case it gets colder than expected.

    The instruments are:

    — Alice: A 10-pound ultraviolet imaging spectrometer built by the Southwest Research Institute to study the structure and composition of Pluto’s atmosphere. It also will be used to look for signs of a charged ionosphere around Pluto and any traces of an atmosphere around Charon.

    — Ralph: A 23-pound telescope/camera system developed by Ball Aerospace Corp., NASA’s Goddard Space Flight center and the Southwest Research Institute that includes a multi-spectral visible-light camera with seven black-and-white and color CCD detectors and a single infrared channel for spectroscopic studies.

    Operating in light 1,000 times dimmer than on Earth, Ralph will photograph the sunlit surfaces of Pluto and Charon, providing stereoscopic views, measuring the temperature and mapping abundances of nitrogen, methane, carbon monoxide and water ice. In black-and-white mode, the camera will be able to discern surface features three-tenths of a mile across (0.9 miles across in color mode and 4.3 miles in infrared mode).

    — Radio Science Experiment (REX): This is a 3.5-ounce circuit board incorporated in the spacecraft’s radio system that was developed by Johns Hopkins and Stanford University. As the spacecraft flies behind Pluto and Charon, radio waves from Earth will be bent slightly as they pass through atmospheric gases. By characterizing those subtle changes, scientists will be able to gain insights into atmospheric temperature and pressure.

    — LORRI (Long-Range Reconnaissance Imager): A 19-pound digital camera equipped with an 8.2-inch telescope serving as a telephoto lens that was used for optical navigation on the way to Pluto. At close approach, LORRI, developed by Johns Hopkins, should be capable of detecting surface features as small as 82 feet across.

    — SWAP (Solar Wind at Pluto): Developed by the Southwest Research Institute, SWAP will study how Pluto interacts with the solar wind. Scientists believe Pluto loses about 165 pounds of its atmosphere every second. That material is then ionized by sunlight and carried away on the solar wind.

    — PEPSSI (Pluto Energetic Particle Spectrometer Science Investigation): A 3.3-pound spectrometer developed by Johns Hopkins to study material escaping from Pluto’s atmosphere as well as the atmosphere itself.

    — SDC (Student Dust Counter): The only instrument that will remain on for the duration of the New Horizons mission, the SDC was developed by students at the University of Colorado at Boulder to measure microscopic dust grains in interplanetary space.

    “By the time we are done, we will have mapped Pluto and Charon and the small moons for their geology,” Stern said. “We will have mapped their surface temperatures and their surface compositions. We will measure Pluto’s atmosphere, determine its structure, its escape rate and its composition.

    “We will address whether Pluto or Charon have interior oceans, and they might. We will search for new satellites and possible rings in the system and we’ll do more. There’s going to be a rich variety of datasets about this strange and mysterious system.”

    But Pluto is not the end of the road for New Horizons. Mission managers are studying two KBOs along the spacecraft’s trajectory and hope to fly past at least one of them in 2019. After that, the spacecraft will move on into interstellar space, leaving humanity behind forever.

    Fittingly, it will not be alone.

    The spacecraft is carrying a CD-ROM with the names of 434,000 enthusiasts, photos of the New Horizons project personnel, quarters from Florida, where the probe was launched, and Maryland, where it was built, and a small piece of Burt Rutan’s SpaceShipOne, the first privately-funded manned spacecraft.

    And mounted on the side of New Horizons is a small container housing some of the ashes of Clyde Tombaugh.

    “Interned herein are remains of American Clyde W. Tombaugh,” the inscription reads. “Discoverer of Pluto and the solar system’s ‘third zone.’ Adelle and Muron’s boy. Patricia’s husband, Annette and Alden’s father, astronomer, teacher, punster and friend. Clyde W. Tombaugh (1906 — 1997)”

    Link to article
    NASA probe finally on Pluto’s doorstep | Spaceflight Now
     
    EuroMode

    EuroMode

    Active Member
    NASA just found something big hiding out behind Pluto



    NASA and the team behind its New Horizons spacecraft announced today that Pluto — the dwarf planet — has a giant tail.

    It's not a physical tail like a dog's, of course, but rather a frigid cloud of ionized gases trailing an estimated 48,000 to 68,000 miles behind Pluto, according to a NASA press release.

    This giant tail is actually part of Pluto's atmosphere. Except that the bits of atmosphere are being stripped away by solar wind, a torrent of electrically-charged particles that constantly pours out of the sun in all directions.

    "We see the atmosphere way far out," Randy Gladstone, a New Horizons co-investigator at Southwest Research Institute in San Antonio, said during a NASA press conference on Friday. "We see it from the ground out to 1,000 miles above the surface."

    Because Pluto is such a tiny planet — its a fraction of a percent as massive as the Earth — its atmosphere escapes directly into space, Gladstone said.

    Gladstone and others discovered the tail after examining data from the Solar Wind Around Pluto (SWAP) instrument on the New Horizons spacecraft. The device found an anomaly in the solar wind around Pluto: a depression composed of nitrogen ions. This depression is the tail, and it extends an unknown length behind the planet.

    "We have actually flown through this [tail]," Fran Bagenal, a New Horizons co-investigator from the University of Colorado, Boulder, said during the press conference.

    Ionized gas forms when a bunch of energy pummels atmospheric atoms and molecules. This bombardment pops electrons off the atmospheric gas particles, allowing their electrons to freely circulate. The end result is plasma: a fourth state of matter after solids, liquids, and gases.

    As far as we know, plasma is the most common state of matter in the universe. There's simply a lot of energy pouring out of stars, and a lot of gas floating in space to form plasma. So, while it might seem surprising, plasma tails like Pluto's aren't new. They even exist behind other planets in the Solar System, including Venus and Mars.

    The team still hasn't determined the precise shape of Pluto's newly discovered tail. They also don't know exactly how the was formed.

    So, NASA is anxiously waiting for New Horizons to beam back more data. By August the team hopes to calculate how fast Pluto is losing its atmosphere to space — and, likewise, how quickly the icy world is shrinking.

    source businessinsider
     
    Dynamite Joe

    Dynamite Joe

    Well-Known Member
    University of Cambridge

    Scientists identify exoplanets where life could develop as it did on Earth



    Scientists have identified a group of planets outside our solar system where the same chemical conditions that may have led to life on Earth exis


    This work brings us just a little bit closer to addressing the question of whether we are alone in the universe.
    Paul Rimmer​
    The researchers, from the University of Cambridge and the Medical Research Council Laboratory of Molecular Biology (MRC LMB), found that the chances for life to develop on the surface of a rocky planet like Earth are connected to the type and strength of light given off by its host star.
    Their study, published in the journal Science Advances, proposes that stars which give off sufficient ultraviolet (UV) light could kick-start life on their orbiting planets in the same way it likely developed on Earth, where the UV light powers a series of chemical reactions that produce the building blocks of life.
    The researchers have identified a range of planets where the UV light from their host star is sufficient to allow these chemical reactions to take place, and that lie within the habitable range where liquid water can exist on the planet’s surface.
    “This work allows us to narrow down the best places to search for life,” said Dr Paul Rimmer, a postdoctoral researcher with a joint affiliation at Cambridge’s Cavendish Laboratory and the MRC LMB, and the paper’s first author. “It brings us just a little bit closer to addressing the question of whether we are alone in the universe.”
    The new paper is the result of an ongoing collaboration between the Cavendish Laboratory and the MRC LMB, bringing together organic chemistry and exoplanet research. It builds on the work of Professor John Sutherland, a co-author on the current paper, who studies the chemical origin of life on Earth.
    In a paper published in 2015, Professor Sutherland’s group at the MRC LMB proposed that cyanide, although a deadly poison, was in fact a key ingredient in the primordial soup from which all life on Earth originated.
    In this hypothesis, carbon from meteorites that slammed into the young Earth interacted with nitrogen in the atmosphere to form hydrogen cyanide. The hydrogen cyanide rained to the surface, where it interacted with other elements in various ways, powered by the UV light from the sun. The chemicals produced from these interactions generated the building blocks of RNA, the close relative of DNA which most biologists believe was the first molecule of life to carry information.
    In the laboratory, Sutherland’s group recreated these chemical reactions under UV lamps, and generated the precursors to lipids, amino acids and nucleotides, all of which are essential components of living cells.
    “I came across these earlier experiments, and as an astronomer, my first question is always what kind of light are you using, which as chemists they hadn’t really thought about,” said Rimmer. “I started out measuring the number of photons emitted by their lamps, and then realised that comparing this light to the light of different stars was a straightforward next step.”
    The two groups performed a series of laboratory experiments to measure how quickly the building blocks of life can be formed from hydrogen cyanide and hydrogen sulphite ions in water when exposed to UV light. They then performed the same experiment in the absence of light.
    “There is chemistry that happens in the dark: it’s slower than the chemistry that happens in the light, but it’s there,” said senior author Professor Didier Queloz, also from the Cavendish Laboratory. “We wanted to see how much light it would take for the light chemistry to win out over the dark chemistry.”
    The same experiment run in the dark with the hydrogen cyanide and the hydrogen sulphite resulted in an inert compound which could not be used to form the building blocks of life, while the experiment performed under the lights did result in the necessary building blocks.
    The researchers then compared the light chemistry to the dark chemistry against the UV light of different stars. They plotted the amount of UV light available to planets in orbit around these stars to determine where the chemistry could be activated.
    They found that stars around the same temperature as our sun emitted enough light for the building blocks of life to have formed on the surfaces of their planets. Cool stars, on the other hand, do not produce enough light for these building blocks to be formed, except if they have frequent powerful solar flares to jolt the chemistry forward step by step. Planets that both receive enough light to activate the chemistry and could have liquid water on their surfaces reside in what the researchers have called the abiogenesis zone.

    Among the known exoplanets which reside in the abiogenesis zone are several planets detected by the Kepler telescope, including Kepler 452b, a planet that has been nicknamed Earth’s ‘cousin’, although it is too far away to probe with current technology. Next-generation telescopes, such as NASA’s TESS and James Webb Telescopes, will hopefully be able to identify and potentially characterise many more planets that lie within the abiogenesis zone.
    Of course, it is also possible that if there is life on other planets, that it has or will develop in a totally different way than it did on Earth.
    “I’m not sure how contingent life is, but given that we only have one example so far, it makes sense to look for places that are most like us,” said Rimmer. “There’s an important distinction between what is necessary and what is sufficient. The building blocks are necessary, but they may not be sufficient: it’s possible you could mix them for billions of years and nothing happens. But you want to at least look at the places where the necessary things exist.”
    According to recent estimates, there are as many as 700 million trillion terrestrial planets in the observable universe. “Getting some idea of what fraction have been, or might be, primed for life fascinates me,” said Sutherland. “Of course, being primed for life is not everything and we still don’t know how likely the origin of life is, even given favourable circumstances - if it’s really unlikely then we might be alone, but if not, we may have company.”
     
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